Thermal ink jet printers have experienced great commercial success since they were invented back in the early 1980's. To accommodate the users of today, it has become very important for these ink jet printers to go faster and faster with each new generation. The same users also want improved print quality at these faster speeds. The dots used to construct ink jet characters have gotten progressively smaller to meet the print quality demands. Naturally, as the dots get smaller, more dots are required to construct each character. Although manufacturing of these printheads have progressed as well, it is very difficult to get the exact same size dot to come out of every printhead. The range of acceptable dot sizes is quite narrow; however, a printhead that generates dots on the large side of that range will create characters that their composition of larger dots has overlapped to the point that the media it is printed on becomes wetter and the edges of the characters or images become less defined.
The wet media problem is only compounded by the faster speeds of the newer ink jet printers. The ink jet printing industry has been very successful at maximizing the speed of the ink jet printers while improving the print quality. The problem associated with increasing the speed has been ink dry time. At higher speeds, the ink on one page is not fully dry before another page is printed and dropped on top of it in the output tray of the printer. This results in smearing or blotting between pages. The easiest solution to this problem was to slow down the printers that engineers had worked so hard to speed up and add in a hold time to allow each page sufficient dry time before the next sheet was printed and dropped on top of it. This decreased the throughput of the printer. This was not an acceptable solution to consumers.
A better solution to the problem was to add in a one-sheet hold buffer. This was accomplished by sliding the page onto a set of output rails, or wings, that suspends the sheet above the output tray as it was being printed, allowing the previously printed sheet in the tray below to dry. When the printing of a page was completed, the output rails would drop the sheet onto the now dry sheet below. This is the method used today in ink jet printers.
Now the newest printers on the market have gotten so fast that they have outran the ability to consistently get the sheet dry by using the one-sheet hold buffer method. Consumers continue to want faster printers at an even higher performance. In order to avoid returning to the point of compromising speed to eliminate smearing or blotting between pages, future ink jet printers must develop yet another solution.